We believe that roots, primarily Greek and Latin, are an important knowledge component of words. In fact, Membean teaches more word roots than any other program online. The learner will learn close to 1000 word roots by the time they finish learning vocabulary through Membean.
Membean's primary focus, however, is on individual words. Roots are one of eight different ways that we teach words. A purely morphological instruction of words is not the most effective word-learning strategy, although roots certainly enhance the learning process and are effective mnemonically.
We do place emphasis upon word roots, but we also strongly believe that context, definition, and word relationships are equally important for nuanced word knowledge. You can see all the ways that Membean teaches words, including word roots, here.
We have a collection of rootcasts, and many of our teachers designate time in their classes to listen to them, or have their students listen to them for homework.